That's my master cylinder from a few years ago as an example of "mixed DOT3/4 + DOT5" Hopefully HeisenBob's master cylinder is better. I fixed mine a few years agoPersonally I would shop vac the fluid from that master cylinder and replace the entire master cylinder, calipers and wheel cylinders. While I was at it I would change the rear axle seals and repack the front wheel bearings and spindle bearings. Do it right. It will cost less than $200. for all the parts and you can do it all in 1 day. I have done it many times. You will not revisit the brake system in many miles. What you have there is a mess. Good Luck. Be Safe.